1) under the weather means not feeling well.
2) It means that a person is currently unemployed — having quit, been fired, or laid off from his or her previous job, or the previous job was temporary and has now ended — and the person has not yet found a new job.
acid chowder, barking at the ants, the big spit, arguing with the worms, etc.
well-seasoned, experienced, elderly, time lasted, antique
You use "it's" as a formal Contraction, it's short for 'it is' or 'it has'.
For example, 'it's a wonderful day's
You use "so" when you are describing something
For example, 'it's so hot'
"So" is also another word for "very", which is where the word originally generated. it's often mixed up with "such", but dont worry! you'll learn English alot soon!
